The primary objectives of the Core are 1) to assure the integrated, coherent, and effective implementation of the Program and 2) to provide basic neuromedical, virological, and neuropsychiatric characterization of Program participants. To perform its duties in an efficient and accountable manner, the Core has been organized into five interacting units which are complemented by resources available through the HIV Neurobehavioral Research Center (HNRC). The Executive Unit is responsible for coordinating the activities of the Program on a day-to-day basis and has specific responsibility for the monitoring of protocol implementation and maintenance of effective communications internally between investigators and staff and externally between the Program and the University, the community, and the Agency. The Participant Accrual and Retention (PAR) Unit is responsible for identification, recruitment, consenting, and follow-up of participants. The PAR Unit also coordinates and monitors human subjects affairs, and reports to the Program Director on participant issues. The Assessment Unit is responsible for neuromedical evaluations and the collection and analysis of blood and CSF specimens from all participants. This Unit will also assess each participant s psychiatric and substance use history. In addition, Assessment Unit personnel will provide evaluation results to participants and, with consent, to service providers. The Data Management Unit provides the conceptual framework, procedures, software, hardware, and quality control mechanisms required to manage a complex and interactive set of data. The Statistics Unit consults with Projects on design and data analysis plans, statistical modeling, the reduction of data to composite variables, advanced analyses, including longitudinal, logistic, and survival analyses (with particular emphasis on cross-project analyses), and explores new statistical methods of analysis while addressing Program-related research questions. Beyond the above described five units, the Core also coordinates the activities of critical internal and external working groups within the Program. The internal groups include the Council of Investigators (sets policy and reviews scientific progress on a regular basis); the Director s Staff (assists in the practical management of the Program); the Data, Statistics, and Publications Committee (reviews analyses and manuscripts); and the Confidentiality Committee, (monitors human subjects protection). The external groups include the Participant s Advisory Board (provides feedback from participants to the Director); the Community Advisory Board (provides advice and feedback on the functioning of the Program in various communities); and the Scientific Advisory Board (provides periodic independent review of our progress).